Fix regression causing pasted images to have a zero-size transform (#2238)

* Use the identity matrix as the default for an image frame

* Fix all usages to be equivalent to their pre-refactor versions, opting to keep ZERO not IDENTITY as the default image size

---------

Co-authored-by: Keavon Chambers <keavon@keavon.com>

node-graph/gstd/src/brush.rs

@@ -272,7 +272,7 @@ fn brush(_: Footprint, image: ImageFrameTable<Color>, bounds: ImageFrameTable<Co
 		let opaque_image = ImageFrame {
 			image: Image::new(bbox.size().x as u32, bbox.size().y as u32, Color::WHITE),
 			transform: background_bounds,
-			..Default::default()
+			alpha_blending: Default::default(),
 		};
 		let mut erase_restore_mask = opaque_image;
 

node-graph/gstd/src/raster.rs

@@ -627,7 +627,7 @@ fn mandelbrot(footprint: Footprint) -> ImageFrameTable<Color> {
 			..Default::default()
 		},
 		transform: DAffine2::from_translation(offset) * DAffine2::from_scale(size),
-		..Default::default()
+		alpha_blending: Default::default(),
 	};
 
 	ImageFrameTable::new(result)

node-graph/gstd/src/wasm_application_io.rs

@@ -87,7 +87,8 @@ fn decode_image(_: (), data: Arc<[u8]>) -> ImageFrameTable<Color> {
 			height: image.height(),
 			..Default::default()
 		},
-		..Default::default()
+		transform: glam::DAffine2::IDENTITY,
+		alpha_blending: Default::default(),
 	};
 
 	ImageFrameTable::new(image)